首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   13706篇
  免费   1158篇
  国内免费   54篇
耳鼻咽喉   77篇
儿科学   573篇
妇产科学   356篇
基础医学   1622篇
口腔科学   366篇
临床医学   1434篇
内科学   3408篇
皮肤病学   256篇
神经病学   1281篇
特种医学   520篇
外国民族医学   8篇
外科学   1834篇
综合类   274篇
预防医学   1039篇
眼科学   292篇
药学   869篇
中国医学   3篇
肿瘤学   706篇
  2021年   165篇
  2020年   108篇
  2019年   205篇
  2018年   229篇
  2017年   186篇
  2016年   170篇
  2015年   212篇
  2014年   292篇
  2013年   413篇
  2012年   613篇
  2011年   640篇
  2010年   340篇
  2009年   315篇
  2008年   519篇
  2007年   605篇
  2006年   604篇
  2005年   560篇
  2004年   601篇
  2003年   531篇
  2002年   486篇
  2001年   456篇
  2000年   396篇
  1999年   402篇
  1998年   137篇
  1997年   124篇
  1996年   141篇
  1995年   111篇
  1994年   129篇
  1993年   113篇
  1992年   339篇
  1991年   315篇
  1990年   312篇
  1989年   323篇
  1988年   250篇
  1987年   272篇
  1986年   260篇
  1985年   269篇
  1984年   201篇
  1983年   159篇
  1982年   100篇
  1979年   216篇
  1978年   150篇
  1977年   146篇
  1976年   117篇
  1975年   150篇
  1974年   166篇
  1973年   142篇
  1972年   154篇
  1971年   118篇
  1970年   113篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Modified-release opioids are often prescribed for the management of moderate to severe acute pain following total hip and knee arthroplasty, despite recommendations against their use due to increasing concerns regarding harm. The primary objective of this multicentre study was to examine the impact of modified-release opioid use on the incidence of opioid-related adverse events compared with immediate-release opioid use, among adult inpatients following total hip or knee arthroplasty. Data for total hip and knee arthroplasty inpatients receiving an opioid analgesic for postoperative analgesia during hospitalisation were collected from electronic medical records of three tertiary metropolitan hospitals in Australia. The primary outcome was the incidence of opioid-related adverse events during hospital admission. Patients who received modified with or without immediate-release opioids were matched to those receiving immediate-release opioids only (1:1) using nearest neighbour propensity score matching with patient and clinical characteristics as covariates. This included total opioid dose received. In the matched cohorts, patients given modified-release opioids (n = 347) experienced a higher incidence of opioid-related adverse events overall, compared with those given immediate-release opioids only (20.5%, 71/347 vs. 12.7%, 44/347; difference in proportions 7.8% [95%CI 2.3–13.3%]). Modified-release opioid use was associated with an increased risk of harm when used for acute pain during hospitalisation after total hip or knee arthroplasty.  相似文献   
2.
BackgroundCampylobacter spp. are one of the commonest causes of diarrhea in children under five and in resource poor settings also lead to malabsorption and stunting. The purpose of this systematic review was to understand the burden of Campylobacter spp. associated diarrhea among children in the South Asian countries.MethodsThis systematic review followed the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analysis) guidelines. Databases were searched with defined keywords for publications from the years 1998–2018. Data on proportion of positive samples was extracted to compare the rates of Campylobacter infection among children (under the age of 19) from different study populations.ResultsOf the 359 publications screened, 27 eligible articles were included in this systematic review and categorized based on study design. In 8 case-control studies, Campylobacter spp. was detected more frequently among diarrheal cases (range, 3.2–17.4%) than non-diarrheal cases (0–13%). Although there were variations in the study population, overall, children under the age of two years experienced Campylobacter diarrhea more often than older children. Most studies reported stool culture as the method used to detect Campylobacter spp. however retesting using PCR-based methods significantly increased detection rates. Limited data were available on Campylobacter species. In 4 studies that provided species data, C. jejuni (3.2–11.2%) was shown to be the most common species, followed by C. coli.ConclusionIn South Asia, Campylobacter spp. are one of the most common bacterial diarrheal pathogens affecting children but there is a paucity of data on species, risk factors and attributable sources. Although a few studies were available, the epidemiology of campylobacteriosis remains uncertain. To understand the true burden and sources of infection, more detailed studies are needed collecting data from human, animal and environmental sources and using both culture and genomic tools.  相似文献   
3.
Study objectiveIn the Emergency Department (ED) setting, clinicians commonly treat severely elevated blood pressure (BP) despite the absence of evidence supporting this practice. We sought to determine if this rapid reduction of severely elevated BP in the ED has negative cerebrovascular effects.MethodsThis was a prospective quasi-experimental study occurring in an academic emergency department. The study was inclusive of patients with a systolic BP (SBP) > 180 mm Hg for whom the treating clinicians ordered intensive BP lowering with intravenous or short-acting oral agents. We excluded patients with clinical evidence of hypertensive emergency. We assessed cerebrovascular effects with measurements of middle cerebral artery flow velocities and any clinical neurological deterioration.ResultsThere were 39 patients, predominantly African American (90%) and male (67%) and with a mean age of 50 years. The mean pre-treatment SBP was 210 ± 26 mm Hg. The mean change in SBP was ?38 mm Hg (95% CI ?49 to ?27) mm Hg. The average change in cerebral mean flow velocity was ?5 (95% CI ?7 to ?2) cm/s, representing a ?9% (95% CI ?14% to ?4%) change. Two patients (5.1%, 95% CI 0.52–16.9%) had an adverse neurological event.ConclusionWhile this small cohort did not find an overall substantial change in cerebral blood flow, it demonstrated adverse cerebrovascular effects from rapid BP reduction in the emergency setting.  相似文献   
4.

Purpose

A hydrogel rectal spacer (HRS) is a medical device that is approved by the U.S. Food and Drug Administration to increase the separation between the prostate and rectum. We conducted a cost-effectiveness analysis of HRS use for reduction in radiation therapy (RT) toxicities in patients with prostate cancer (PC) undergoing external beam RT (EBRT).

Methods and Materials

A multistate Markov model was constructed from the U.S. payer perspective to examine the cost-effectiveness of HRS in men with localized PC receiving EBRT (EBRT alone vs EBRT + HRS). The subgroups analyzed included site of HRS placement (hospital outpatient, physician office, ambulatory surgery center) and proportion of patients with good baseline erectile function (EF). Data on EF, gastrointestinal and genitourinary toxicities incidence, and potential risks associated with HRS implantation were obtained from a recently published randomized clinical trial. Health utilities and costs were derived from the literature and the 2018 Physician Fee Schedule and were discounted 3% annually. Quality-adjusted life years (QALYs) and costs were modeled for a 5-year period from receipt of RT. Probabilistic sensitivity analysis and value-based threshold analyses were conducted.

Results

The per-patient 5-year incremental cost for spacers administered in a hospital outpatient setting was $3578, and the incremental effectiveness was 0.0371 QALYs. The incremental cost-effectiveness ratio was $96,440/QALY for patients with PC undergoing HRS insertion in a hospital and $39,286/QALY for patients undergoing HRS insertion in an ambulatory facility. For men with good baseline EF, the incremental cost-effectiveness ratio was $35,548/QALY and $9627/QALY in hospital outpatient and ambulatory facility settings, respectively.

Conclusions

Based on the current Medicare Physician Fee Schedule, HRS is cost-effective at a willingness to pay threshold of $100,000. These results contain substantial uncertainty, suggesting more evidence is needed to refine future decision-making.  相似文献   
5.
6.
7.
8.
The main purpose of this study was to assess whether it is possible to improve the prognostic impact of international prognostic index (IPI) score by combining it with peripheral blood counts. Thus, we evaluated the prognostic power of lymphocyte, neutrophil, and monocyte counts in 520 patients with diffuse large B cell lymphoma treated with R-CHOP, confirming that these parameters have a strong impact on overall survival (OS). Using revised IPI (R-IPI), 44% of patients were categorized as poor-risk and showed an OS at 5 years of 46%. As OS at 5 years of the 520 patients is 67%, it is clearly evident that R-IPI tends to overestimate the proportion of patients with poor prognosis. Accordingly, in an attempt to improve the discriminating power of R-IPI, we evaluated and compared three different scores by combining the neutrophil lymphocyte ratio (NLR) and absolute monocyte count (AMC) with the following values: (a) IPI score 3-5, (b) age > 60 years and performance status, (c) age ≥ 65 years and LDH > ULN. The three indexes studied, had a similar 5 years OS for the high-risk group (46%-52%), but the proportion of patients classified as poor-risk were 37%, 20%, and 32%, respectively, which are lower than 44% identified with R-IPI. Thus, while R-IPI overestimates the number of high-risk patients, after applying our models, it is possible to recognize patients who are truly at high-risk. Of the three scores, the most accurate appears to be that based on NLR, AMC, LDH > ULN and age ≥ 65 years, which identifies 32% of high-risk patients, correlating well with what is seen in clinical practice.  相似文献   
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号